The present invention relates to a crusher which crushes things such as waste, wood, plastic and the like, and more particularly, to a crusher which crushes such things utilizing cutting disks.
Japanese Patent Publication (KOHYO) No. 58-500,890 discloses a crusher of this kind. Referring to FIGS. 1 and 2, this crusher is provided with a casing 3 fixed to a base 4 and having an inlet 1 and an inlet 2, screws 5a, 5b, and 5c rotatably mounted in the casing 3 in parallel with each other, and a motor 6 connected to the screws 5a, 5b and 5c for driving the screws 5a, 5b, and 5c. A spiral cutting blade 8a is mounted at regular pitches on a circumferential surface of a shaft 7a of the first screw 5a. A spiral cutting blade 8b is mounted at the same pitch as the above-described pitch on a circumferential face of a shaft 7b of the second screw 5b. A spiral cutting blade 8c is mounted at the same pitch as the above-described pitch on a circumferential face of a shaft 7c of the third screw 5c.
As shown in FIG. 2, waste introduced from the inlet 1 of the casing 3 into the space between the screws 5a and 5b and between the screws 5b and 5c is compressed, cut, and shredded by the cutting blades 8a, 8b, and 8c. At this time, the cutting blades 8a rotates counterclockwise and the cutting blades 8b and 8c rotate clockwise. Thereafter, the crushed pieces are discharged from the outlet 2.
However, the crusher has a disadvantage in that the waste is not crushed more than once by the cutting blades 8a, 8b, and 8c while the screws 5a, 5b, and 5c rotate for 360.degree..
The crusher has another disadvantage in that if the waster includes stiff foreign matter, the foreign matter is sandwiched between the adjacent screws 5a and 5b and/or between the adjacent screws 5b and 5c. As a result, the shafts 7a, 7b, and/or 7c may be stopped and this may stop the crushing operation. In addition, part of the screws 5a, 5b, and/or 5c may be broken, which necessitates the replacement of the screw(s).
Another related art is disclosed in Japanese Utility Model Laid-open Publication No. 48-63389. A crusher assembly disclosed therein is provided with a first crusher consisting of crushing rollers or a compressing roller which crushes waste into large pieces. The crusher assembly is also provided with a second crusher consisting of a rotating drum and a fixed blade which crushes the large crushed pieces into small pieces. The first crusher is mounted on an upper portion of the crusher assembly and the second one is mounted on a lower portion thereof. This causes the crusher assembly to be large, so that a large space is required for installing it and further, the crusher may fail easily because it employs many parts.